Enhancement request: Allow to customize output file format from command line or subscription file

[fovea1959]

Near as I can tell, the only way to modify the output file name is to edit upodder.py and change FILENAME.

A nice enhancement would be to add a command line switch
--filename="{entry_date} {entry_title}.{filename_extension}"

[fovea1959]

oh! done! Can you please pull from https://github.com/russ-p/upodder ?